For virtual display feature, as there is no dce engine, so no pageflip irq
generated. So directly call pageflip irq funtion when received vysn interrupt.
Signed-off-by: Emily Deng <Emily.Deng@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>